1. Field of Invention
The invention relates to a cleaning device for a machine tool, which is adapted to remove chips that affect the changing of tools during a tool change by an automatic tool change mechanism.
2. Description of Related Art
In various types of machining tools, such as a machining center, a cutting fluid supply device is provided for supplying a large amount of cutting fluid or coolant to a portion of a workpiece that is subject to machining by a tool, in order to improve the machining capability of the tool, to improve the machining accuracy and to prolong the service life of the tool.
In the above type of machine tool, chips resulting from the machining process tend to scatter around the tool and the workpiece. To avoid scattering of the chips, a cover is provided which surrounds the tool and the workpiece.
If the tool and the workpiece are surrounded by the cover, however, the size and cost of the equipment are undesirably increased, and more frequent cleaning is required for removing the chips.
In a cutting fluid supply device as disclosed in Japanese laid-open Patent Publication No. 6-238543, a curtain consisting of a coolant fluid is formed around a cutting location where a workpiece is machined by the tool, so as to avoid the scattering of chips.
In the known cutting fluid supply device, however, scattering of chips may be prevented by the coolant curtain, but the coolant fluid spatters or splashes, to adhere to various portions of the machine tool. In some cases, the coolant contains chips, or chips adhere to the spattering coolant.
If such chips are transferred onto a shank of a tool, or the like, the chips may affect the changing of tools by an automatic tool change mechanism, resulting in a reduced machining accuracy.
It is therefore an object of the invention to provide a cleaning device for a machining tool, which is able to remove chips, and the like, that affect the changing of tools.
To accomplish the object, the invention provides a cleaning device for a machine tool including an automatic tool change mechanism adapted to replace a tool attached to a main shaft by another tool, a pump that supplies coolant, and a cutting fluid nozzle that emits the coolant supplied from the pump, toward a location where a workpiece is machined by the tool, the cleaning device comprising at least one cleaning nozzle that emits clean coolant toward at least one portion of the machine tool where adherence of chips affects the changing of tools.
In the operation of the cleaning device of the invention, jets of clean coolant are emitted from the cleaning nozzles to locations where adherence of chips affects the changing of tools, thus avoiding such problems as a reduction in the machining accuracy and damage to tools, which would otherwise occur due to the adherence of chips to the tool.
In one preferred form of the invention, the cleaning device further includes a filter that purifies the coolant supplied from the pump, and supplies the purified coolant to the above-indicated at least one cleaning nozzle.
By use of the filter through which coolant is supplied from the coolant pump to the cleaning nozzles, purified coolant can be easily obtained.
In another preferred form of the invention, the cleaning device further includes a directional control valve that is placed in a selected one of a first position in which the coolant is supplied from the pump to the cutting fluid nozzle, and a second position in which the coolant is supplied from the pump to the above-indicated at least one cleaning nozzle.
With the above arrangement in which the coolant is selectively supplied to the cutting fluid nozzle or cleaning nozzles through the directional control valve, the cleaning device of the invention can be easily introduced or incorporated into conventional equipment or machines.
In a further preferred form of the invention, the automatic tool change mechanism includes a swing arm adapted for changing tools and an air cylinder that produces an air pressure for driving the swing arm. In this form, the directional control valve is switched from the first position to the second position in response to the air pressure of the air cylinder upon driving of the swing arm.
Thus, the directional control valve can be switched from the first position to the second position only by applying the air pressure of the air cylinder to the valve upon a change of tools or upon driving of the swing arm. This eliminates a need to provide a special control system for effecting switching of the directional control valve.
In a still another preferred form of the invention, the cleaning nozzles emit jets of the coolant during a tool changing operation of the automatic tool changing mechanism. In this case, cleaning can be effectively accomplished in a short time, and the tool change can be carried out in a state in which the tool and its surroundings have been just cleaned.
In another preferred form of the invention, the above-indicated at least one cleaning nozzle includes a first cleaning nozzle that emits a jet of the coolant toward a tool holder to which the tool is attached during the changing of tools by the automatic tool changing mechanism. Thus, the coolant is ejected from the first cleaning nozzle so that the tool holder is surely or thoroughly cleaned.
In the above form of the invention, the first cleaning nozzle may emit the coolant toward at least a shank portion of the tool holder. In this case, the shank portion to which chips are most likely to adhere can be surely cleaned.
In the above form of the invention, the first cleaning nozzle may include a nozzle hole that is open downwards, and an inclined wall that faces an opening of the nozzle hole and is inclined so as to direct the coolant from the nozzle hole toward the tool. With this arrangement, the coolant from the first cleaning nozzle is directed toward the tool after impinging upon the inclined wall.
In the above form of the invention, the first cleaning nozzle may be formed in a ring-like shape, and include a plurality of nozzle holes that are open downwards and arranged along substantially the same circle, and an inclined wall that is formed continuously in a circumferential direction, the inclined wall facing openings of the nozzle holes and being inclined so as to direct the coolant from the nozzle holes toward the tool.
Since the inclined wall is formed continuously in the circumferential direction, the coolant ejected from each of the nozzle holes spreads over a sufficiently wide area, and flows of coolant from the adjacent nozzle holes are joined together, to form a coolant film or curtain having an inverted conical shape around the main shaft, so that the coolant is directed toward the center of rotation of the main shaft. Thus, the coolant is uniformly sprayed completely over the entire periphery of the tool holder to effect highly efficient cleaning. Also, if the nozzle holes and the ring-like inclined wall are formed in a single member, the manufacturing cost is reduced, and the mounting procedure can be simplified.
In another preferred form of the invention, the above-indicated at least one cleaning nozzle includes a plurality of cleaning nozzles with a plurality of inclined walls having different angles of inclination. In this case, different portions of the tool holder can be effectively cleaned by the coolant ejected from the cleaning nozzles.
In another preferred form of the invention, the above-indicated at least one cleaning nozzle further includes a second cleaning nozzle that emits a jet of the coolant toward the swing arm of the automatic tool change mechanism. With this arrangement, the coolant is ejected from the second cleaning nozzle so as to surely clean the swing arm of the automatic tool change mechanism.
In another preferred form of the invention, the main shaft has an axis that extends in a vertical direction of the machine tool, and the above-indicated at least one cleaning nozzle further includes a third cleaning nozzle that emits a jet of the coolant toward a lower surface of a main shaft head of the main shaft. With this arrangement, the coolant is ejected from the third cleaning nozzle so as to surely clean the lower surface of the main shaft head.
In another preferred form of the invention, the above-indicated at least one cleaning nozzle further includes a fourth cleaning nozzle that emits a jet of the coolant toward a tool pot of the automatic tool change mechanism. With this arrangement, the coolant is ejected from the fourth cleaning nozzle so as to surely clean the tool pot of the automatic tool change mechanism.